Flotation process



iii

Patented May 10, 1938 UNlTED' STATES FLOTATION PROCESS Samuel Lenher andJoseph Lincoln Gillson, Wilmlngton, DeL, assignors to E. I. du Pont deNemours & Company, Wilmington, Del., a corporation of Delaware NoDrawing. Application June 10, 1933,.

1 Serial No. 675,334

11 Claims. (01. 209l66) This invention relates to the flotation of oresand in particular it relates to a flotation process involving the use ofan oil "as a flotation aid together with a frothing agent.

One object of the invention relates to a flotation process for oresinvolving the pre-emulsiflcation of an oil in water followed bytreatment of the ore with the'said emulsion whereby to float the desiredcomponents of the ore. A further object of the invention pertains to thecombined use of an oil and a sulfate ester salt of a normalstraight-chain primary alcohol having from 8 to 18 carbon atoms. A stillfurther object of the invention comprises the process of floating oresby means of a preformed emulsion of oil in water containing an aikylsulfate ester of the character described. Another object of theinvention comprises a practical method for floating manganese ores bymeans of an oil flotation aid. Other objects of the invention willappear hereinafter.

. The use of oils for the flotation of mineral ores has been known formany years. However, oil flotation methods at the present time arelimited in number as far as commercial practice is concerned for variouspractical reasons, among which may be mentioned the failure of oil tosatisfactorily float certain types of mineral ore, the low yield of highgrade concentrate as compared with other flotation processes and theconsequent high cost andlow economy. In accordance with the presentinvention it has been found that mineral ores can be very efficientlyand satisfactorily floated if the oil which is to serve as the flotationaid is thoroughly emulsified in water prior to the treatment of the ore,the oil in water emulsion then being introduced into the ore pulp to betreated together with a suitable flotation agent. The general functionof the oil is to act as a collector, the flotation agent serving togenerate a foam or froth, and the oil assisting in the flotation byconcentrating the ore in the froth.

It has also been found that mineral ores can be satisfactorily floatedby the combined use of an oil and a sulfate ester salt of a normalstraightchain primary alcohol having from 8 to 18 carbon atoms. Thescope of the invention includes the combined use of the oil and sulfateester salt without prior emulsiflcation of the oil in water, but in thepreferred form of the invention, the oil is first thoroughly emulsifiedin water by the use of sulfate ester salt which serves as an ex--cellent emulsifying agent, the emulsion then being introduced into, the'ore pulp wherein the alkyl ester salt also serves as a frothing agent.

The following examples illustrate the preferred form of the inventionwhich however, are not to be construed as limiting the real scope of theinvention:

Example 1 An emulsion was prepared having the following formula:

Mixed sodium alkyl sulfate esters 0.125 gms. Sulfonated abietene 0.10gms. Crude Mexican petroleum (Panuco) 10 gms. Pine tar creosote 2. gms.10% sodium hydroxide solution.... 5 cc. Water 20 gms.

The above emulsion was prepared by dissolving the sodium alkyl sulfateesters and the sulfonated abietene in water, dissolving the creosote inthe crude petroleum, adding the petroleum mixture to the water solution,and emulsifying in a high speed (e. g., 10,000 R. P. M.) mixer.

Complete emulsiflcation required less than one minute. Theemulsiflcationwas stable and easily extended with water.

The m xed sodium alkyl sulfate ester salts comprised about 50% sodiumn-cetyl sulfate, g

utes and the supernatant liquid siphoned off. The

amount of slime so removed made about 100 grams and analyzed 10% Mn.Then the balance of the ore was placed in a flve liter flotation cell ofthe Callow type in which air is introduced under'pressure from thebottom of the cell. Three thousand cc. of water was added to the cell,and the water-extended emulsion inserted into the cell in lots duringthe operation of the cell until 225 cc. had been added, the pH beingmaintained at approximatey 7.4 during the run by adding small quantitiesof dilute sulphuric acid to neutralize the alkali in the emulsion. Thefroth contained both the manganese content of the ore and also a certainamount of slime. The concentrate contained over forty percent Mncalculated as the element manganese. The tailings analyzed less 'than 3%of manganese.

Example 2 An emulsion was prepared according to the manner described inExample 1 and had the following formula:

Mixed sodium alkyl sulfate esters identical with the mixture de- Theemulsion was extended with 300 cc. of water, making a total of 335 cc.225 cc. of the emulsion prepared as above was used for floatingmanganese ore of the same character and amount as was treated inaccordance with the process of Example 1, and in the manner of Example1, the emulsion being added in 75 cc. lots.

The concentrate contained over 44% Mn, the middlings about 30% and thetailings contained less than 3% Mn.

While in hese examples previous desliming of the ore was carried out inboth cases, it was proven by successful runs that previous desliming ofthe ore was not necessary.

Example 3 500 gms. of ore were treated in the flotation cell withoutdesliming, and 300 cc. of a similar emulsion were added. The slime wentwith the concentrate from which it was later removed by dewatering.

bon atoms.

wherein there is a substantial content of humusand humic acids as wellas of slimy material. It is furthermore of greatest effectiveness withthe non-sulfide bearing ores and ores containing me-- tallic compoundswhich are not in the definitely crystallized form.

The alkyl sulfate ester salts which may be used in accordance with thepresent invention arethe water-soluble salts, for example, salts of thefollowing metals: sodium, potassium, ammonium, lithium, magnesium, etc.The alkyl radical of the sulfate ester salts must contain at least 8carbon atoms and preferably from 12 to 18 car- The alkyl sulfate esters,salts of which are 'used in accordance with this invention may beprepared by treating normal straightchain primary alcohols such aslauryl, myristyl, cetyl, oleyl, stearyl and ricinoleyl alcohols (or anyof the alcohols which may be obtained by the catalytic hydrogenation offatty acids, their alkyl esters, or their naturally occurring glyceridesat a temperature of for example 200 to 400 C.)

R-OSO3-Y wherein R represents the residue of a normal primary alcoholcontaining from 8 to 18 carbon atoms and Y represents the residue of asalt forming compound. The proportion of alkyl sulfate ester salt usedmay range within wide limits, e. g., 0.0005% up to 1% but preferablyfrom 0.001% up to 0.05% of the water present during the floating of theore. Where the alkyl sulfate ester salt is used both as an emulsifyingagent and as a frothing agent, all of the ester salt may be introducedinto the emulsion or the amount of ester salt used in the emulsion maybe supplemented by an added amount of ester salt. Either the singlealkyl ester salts or mixtures of the salts may be used.

In forming an emulsion usually an elevated temperature of for example 50to C. may be used altho this temperature is subject to wide variationaccording to the conditions of emulsification. During the floating ofthe ore, it is preferred that ordinary temperature be used, altho thefioating temperature is not critical. The flotation of the ore andparticularly where alkyl sulfate esterfsalts are used may take placeunder either acid or alkaline conditions, e. g., from a range of pH 5 topH 12. It is preferable however, in floating manganese ore, to use a pHof approximately 7. For other ores, the conditions would preferably bealkaline, altho in some cases it may be desirable to have the flotationsolution slightly acid.

It has been found that Mexican crude petroleum is particularly useful infloating manganese ore properly. Other oils may be used either formanganese or other ores which may be floated in the manner described.Oils other than Mexican crude petroleum which may be used are:

crude petroleum obtainable from Venezuela,

as the sulfonated residue obtained in the manu-- facture of lubricatingoil or other oils by treating petroleum fractions with strong sulfuricacid (in such cases an emulsion of the oil in water may be formedwithout the addition of a further emulsifying agent), pine oil, and theother oils already known to the art for the flotation of mineral ores.

The 'use of creosote as illustrated in the above examples during theemulsification of the oil tends to aid ready emulsification and tostabilize the emulsion.

Various emulsifying agents which may be used in preparing the oil inwater emulsion either with or without the alkyl sulfate ester salts are:sulfonated oleic or ricinoleic acid, Twitchells reagent, the naphthalenesulfonic acids, triethanolamines and their derivatives such as soaps ofthe triethanolamines with fatty acids, e. g., oleic. palmitic, andstearic acid, substituted ethylene diamines as the hydrochlorides,resinates, sulfonated rosin, sulfonated abietene (the hydrocarbonobtained by the thermal decomposition of abietic acid with the splittingoff of C02) abietic acid and its salts, condensation products ofabietene or abietene with epichlorhydrin which are sulfonated,sulfonated olefines, the branched chain higher alcohols obtainable fromthe catalytic reduction of carbon monoxide with hydrogen, and thederivatives of these alcohols obtainable by treatment of the alcoholswith strong sul- '.fonating agents, naphthenic acids, their salts andtheir sulfonation products, and other well-known emulsifying agents.

adding a suitable amount of neutralizing agent,

e. g., where it is desired to raise the pH value, sodium hydroxide maybe added during the emulsification process and where it is desired tolower the pH value sulfuric acid may be added during the emulsiflcationprocess or for that matter to.

the water used as the floating medium.

It has been found also that frequently higher normal straight-chainprimary alcohols having.

at least 8 carbon atoms and preferably from 12 to 18 carbon atoms may beused in combination with the emulsifying agent and particularly incombination with the higher alkyl sulfate ester salts.

The function of the oil present during flotation is as a collector, ashas been stated above. Other collectors may be used in addition to theoil, e. g., aikyl xanthates and their salts or esters, mercaptans,thioureas, azo and diazo compounds, thiophenols, thiouramdisulfldes,dithiophosphates, amines such as alkylamines and triethanolamine andthose agents having emulsifying properties and having also frothing orfoaming properties.

The invention in its broader scope may be applied to the floating of oneor other components of. an ore. Thus, by way of example, with aquartz-feldspar ore it is ordinarily desirable to.

float the feldspar from the quartz. The reverse, however, may in somecases be desired. All that is necessary is to choose a flotation agentwhich floats one component of the ore from the remain: der, theflotation agent being chosen according to the component which it isdesired to remove.

The above description and examples are given by way of illustrationonly. Any variation therefrom which conforms to the spirit of theinvention is intended to be included within the sco of the claims.

We claim: r

1. In the process for the oil froth flotation of mineral ores, the stepwhich comprises floating a desired component of the ore in an aqueousmedium containing oil and a water-soluble sulfate ester salt of a normalstraight-chain primary aicohol having at least 8 carbon atoms.

2. In the process for the oil froth flotation of mineral ores, the stepwhich comprises floating a desired component of the ore in an aqueousmedium containing oil and a water-soluble sulfate ester salt of a normalstraight-chain primary al-.

cohol having from 12 to 18 carbon atoms.

3. In the process for the oil froth flotation of mineral ores, the stepwhich comprises floating a desired component of the ore in an aqueousmedium containing oil and the sodium sulfate ester salt'of a normalstraight-chain primary alcohol having from 12 to 18 chrbon atoms.

4. The process of claim 1 characterized in that the oil is firstemulsified in water prior to introducing the oil into the ore to betreated.

5. The process of claim 1 characterized in that the oil is firstemulsified in water prior to introducing the oil into the ore to betreated, the oil in water emulsion being formed in the presence of awater-soluble sulfate ester salt of a normalstraight-chain primaryalcohol having at least 8 carbon atoms.

6. The process of claim 1 characterized in I that the oil is firstemulsified in water prior to introducing the oil into the ore to betreated, the oil in water emulsion being formed in the presence of awater-soluble sulfate ester salt of a normal straight-chain primaryalcohol having from 12 to 18 carbon atoms.

7. A process of floating Cuban manganese ore that comprises dissolvingin water a water-soluble sulfate ester salt of a normal straight-=chainprimary alcohol having from l2 to 18 carbon atoms, adding the watersolution to a mineral oil, rapidly stirring the mixture untilemulsiflcation takes place, introducing the emulsion into a flotationcell containing water and ore, agitating and aerating, and withdrawingthe froth containing the desired component of the ore.

8. In the froth flotation of non-sulfide ores 20 R-OSOa-Y wherein Rrepresents the residue ofa normal primary alcohol containing from 8 to18 carbon atoms, and Y represents the residue of a saltforming compound.r 9. In the froth flotation of manganese ores wherein an aqueoussuspension of manganese ore is agitated and aerated in the presence of apreemulsifled mineral oil flotation agent the step ,5 which comprisesconducting said operation in the presence of a water-soluble compoundhaving the following general formula:

R-OSOs-Y wherein R represents the residue of a normal primary alcoholcontaining from 8 to 18 carbon atoms, and Y represents the residueof asaltforming compound.

10. In the froth flotation of manganese ore wherein an aqueoussuspension of manganese ore is agitated and aerated in the presence of amineral oil flotation agent which has been preemuisifled with a sodiumsulfate ester salt of a normal primary alcohol containing from 12 to 18carbon atoms, the step which comprises conducting said operation in thepresence of a watersoiuble compound having the following generalformula:

R-OSOs-NB.

wherein R represents the residue of a normal primary alcohol containingfrom 12 to 18 carbon atoms.

11. In the froth flotation of non-sulfide ores wherein an aqueoussuspension of ore is agitated and aerated in the presence of a mineraloil flotation agent the step which comprises conducting said operationin the presence of a watersoiuble compound having the following generalformula: l

R OSO3Y

